U.S. Pat. No. 4,935,616 (further described in the Sandia Lab News, vol. 46, No. 19, Sep. 16, 1994) describes a scannerless range imaging system using either an amplitude-modulated high-power laser diode or an array of amplitude-modulated light emitting diodes (LEDs) to completely illuminate a target scene. An improved scannerless range imaging system that is capable of yielding color intensity images in addition to the 3D range images is described in commonly-assigned, U.S. Pat. No. 6,349,174 entitled “Method and Apparatus for a Color Scannerless Range Imaging System”. As used herein, a scannerless range imaging system will be referred to as a “SRI system”. In the formation of a three-dimensional image (which will herein refer to the combination of the intensity image and range image), the SRI system generates an “image bundle”, which includes both the intensity image and a collection of phase offset images which are used to construct the range image. This formation of a three-dimensional image by the SRI system is more fully described in the “Detailed Description of the Invention” section of this disclosure.
The three-dimensional images formed by the SRI system are useful in a variety of applications. In computer graphics, they can be used to construct photorealistic virtual worlds. For example, a prospective buyer could navigate with six degrees of freedom (three degrees due to translation, and three due to rotation) within a photorealistic virtual model of a house that is for sale, the model generated by a collection of three-dimensional images. In forensics, a three-dimensional image permits metrology of the captured scene long after the real scene has been investigated. In computer vision, three-dimensional images from an SRI system can be used in place of the typical stereo imaging design to enhance robot navigation in situations that are dangerous, inaccessible, or costly to humans.
All of these applications benefit from the availability of three-dimensional images of a stationary scene. Other types of applications exist that would benefit from the availability of three-dimensional video sequences (i.e., three-dimensional image sequences indexed in time). For example, three-dimensional video would allow filmmakers to easily incorporate computer graphics objects, such as cartoons or virtual actors, into a video sequence of a real scene in such a way to make the objects appear that they are naturally interacting with the real environment. Knowledge of the depth of objects in a video sequence could be used to aid deletion of objects from the video sequence, or modify lighting or other properties without requiring recapture. A three-dimensional video sequence could also enhance a viewer's experience by allowing the viewer to navigate with six degrees of freedom within the video. However, such a three-dimensional video sequence is beyond the scope of the current SRI system, because the SRI system is only capable of forming single three-dimensional images.
Therefore, there exists a need in the art for a method of generating a three-dimensional video sequence from images captured by a scannerless range imaging system; such a method should have a minimal storage requirement, and be capable of computing each three-dimensional image in the sequence in real time.